Centrifugal fan and pump-wheel.



PATENTED OCT. 8, 1907. G. M. GAPELL.

GENTRIFUGAL FAN AND PUMP WHEEL.

APPLICATION FILED JULY 11, 1906.

UNITED STATES PATENT OFFICE.

GEORGE MARIE OAPELL, OF NEAR STONY STRATFORD, ENGLAND.

CENTRIFUGAL FA1\l' AND PIMP-WHEEL.

which the following is a specification.

This invention relates to improvements in the con struction ofcentrifugal fans and pump wheels, the chief underlying principle ofwhich consists in so constructing and arrar rging the vanes as toinduce, to a maximum degree, a tendency to the production of cavitationor rfegative pressure at the back of the portions of the vanes which aresituated nearest to the center of revolution, thereby creating atendency for the fluid to be urged from the inlet passage into the zoneof direct action which is swept through by the vanes. Such means ofpromoting the flow of the fluid to and throughjthe wheel, will operatein addition to a subsequently created urging force due to centrifugalaction. By such means the output of the fan or pump wheel will beconsiderably in-. creased and the flow through the wheel beinglargelyassisted by an action which is independent of that due to thecentrifugal whirl there will be a less expenditure of the head derivedfrom the latter action in dragging the fluid through the supply passageand accordinglyit will be delivered with an enhanced gage pressure.

To obtain a positive benefit from the action above described, it will benecessary to avoid the counter-Vailing action which would be due t6 thecreation of cavitation or negative pressure at the back of theoutwardlying portions of the vanes. The means which I adopt to promotecavitation behind the inner portions of the vanes and preclude itscreation at the back of the outer portions, consists in arranging thevanes in a series of steps in which each vane of the series is situatedat a greater radial distance from the center of rotation than the vanewhich next precedes it, this means being supplemented by the employmentof a tail blade or tail blades situatedat the back of the terminal vaneof the series or at the back of that vane and other vanes of the.

series. 4

An example of a tail blade adapted to effect more or less eflicientlythe above described purpose will be 1 found in the specification ofmy-prior patent No. 617,520

but I prefer a modification in the construction and are rangement of thetail blade as shown on the accompanying drawings and as will presentlybe described.

An additional tendency to the creation of a negative pressure at theback of the inner portions of the vanes will be derived by adding, toone or more. of the vanes of a series, a scoop-shaped extension whichprojects laterally into the air inlet passage. In general 2. 31's ralityof series of stepped vanes Willbe requisite in which, succeeding theterminal vane of one series which is at the greatest distance from thecenter of rotation,

Specification of Letters Patent. Application filed July 11,1906. SerialNo- 325,696.

Pump-Wheels, of

Patented. 0a; a, 1907.

BEISSUED there is aleading vane of the following series which issituated at the least distance from the center. For

structural reasons, as apart from considerations relating to.fiuidaction, it will often be advisable to employ some vanes which have agreater length than that which would be compatible with the foregoingdescriptionof vane construction. To harmonize this condition which isimposed by considerations relating to the provision of adequatestrength, rigidity and durability in the most econonrical manner withthose which efiicient fluid action demand, I interpose, between each twoa series ofstepped and relatively short vanes, a lengthened vane whichextends to the outer periphery of the wheels and supplants the terminalvane of the series of stepped vanes arid which also, preferably but notnecessar'ily, extends inwards to the minimum advantageous distance ofany vane from the center of rotation and virtually supplants also theleading vane of the succeeding series of stepped vanes.

Various alternatives of vane curvature and arrangement may be adopted,as for example: The vanes which extend to the outer periphery of thewheel may be radial at the extremity, or they may be inclined forward alittle, or they may be inclined backward,'and the tail blade may bestraight or curved in any degree. In respect to this the choice willdepend on the relative importance of the requirements of large output,maximum efficiency and high or low gage pressure.

On the accompanying drawings I have shown four representative examplesof construction.

In these drawings :Figure 1 is ahalf transverse section of'a wheel inwhich, in the left-hand quadrant, is shown 'a form of construction inwhich stepped vanes only are employed and, in the right-hand quadrant,an alternative form of construction in which a' lengthened vane isinterposed between each two consecutive series of stepped vanes. Fig. 2is a plan corresponding to Fig. 1. In these figures the furthestextending portions of the vanes are inclined somewhat in the forwarddirection. Fig. 3 shows a modified form of curvature of the vanes inwhich the furthest portions are inclined backwards, those in theleft-hand quadrant otherwise corresponding to the left-hand quadrant ofFig. 1 and in the right-hand quadrant interposed lengthened vanes areshown of different shape but otherwise as in the right-hand quadrant ofFig. 1.

In these figures a b c and d are four vanes forming a series of steppedvanes as described above, a being situated at the least radial distancefrom the center of revolution and d at the maximum distance, the outeredge of this latter being situated at the periphery of the wheel. Thevanesof the succeeding series are denoted a b c and d respectively. Onaccount of the remoteness of the inner portion of of from thecorresponding portion of a the negative pressure tended to be created atthe back of the latter, by virtue of its onward motion, will be verypronounced, while at the back of the inner portion of b there also willbe a similar tendency but less intense, because there is a portion of awhich follows more closely, and the same is true of the inner portion ofc. To the back of the outer portion of a a portion of b will berelatively close and prevent any tendency to the creation of a negativepressure and the same thing is true, to the same degree, in respect tothe outer portions of b and P. but, inasmuch as d is remote from theback of (1, there would be a strong tendency to the creation of anegative pressure at the back of d were it not for the action of thetail blade 6. This blade is detached from d, is differently inclined andhas a relatively small width of space between its inner edge and theback of the vane d through, which space will pour a stream of fluidsufiicient to aid in counteracting the tendency to cavitation at thisportion of the wheel and leave the urging effect on the flow of thefluid due to cavitation in the inner portion of the vane zoneundiminished by an opposing influence. i Accordingly there will be afull bore discharge of fluid from between the vanes, and the flowthrough the wheel being largely due to the cavitation action, there willbe little or no subtraction from the centrifugal head for this purpose.Thus a wheel, made as above described,- will not only deliver a maximumvolume of fluid but that fluid will be delivered with-3a maximum gagepressure also. I I

The vane a is provided with a laterally extending scoop portion f whichwill have the effect oi augmenting the tendency to cause cavitationbehin the inner portion of a. L

' On the right hand portions of Figs. 1 and 2 are shown vanes g and g ofextended length which are interposed between consecutive series ofstepped vanes h t and h i. In this case g and 9 may be regarded each assupplanting two stepped vanes, namely the last of one series and thefirst of the next. This form of construetion tends to impart increasedstrength, the principle of operation being as before. vAt the back ofthe outward lying portions of g and g tail-blades j and j are fittedlike e and e before mentioned.

In Fig. 3 the vanes are curved backwards-at their outward extremities,otherwise they are constructed and arranged like those previouslydescribed and they are correspondingly lettered. In-this figure thetailblades e e and j 9' are made to conform to the shape of d and g. Thetail-blade may be joined at its inner edge to the vane which precedesit, or close thereto, or it may have its inner edge separated from theback of the preceding vane by an interval wide enough to allow itsaction to be supplemented by a current of air passing through suchinterval from the inlet to the I periphery of the wheel.

The drawing shows a form of wheel which has a single inlet orifice, butit will be obvious that the arrangement is equally applicable to adouble inlet construction and in this latter the central diaphragm mayextend to the outer periphery of the wheel or stop short thereof;

The drawing shows wheels adapted for operating on air. If water or otherfluid is required to be circulated or pumped, the design will requiresome modifications of detail,'bnt such detail forms no portion of thepresent invention.

' Various other modifications and changes in the design and constructionof my improved centrifugal fan and pump wheels may be resorted towithout departing from the spirit of the invention or sacrificing any ofits advantages, and the different improvements may of course, beemployed separate from each other, such, for example, as the employmentof the main vanes extending inwardly from the periphery together withthe tail-blades located back of them, as described, without intermediatevanes, or the employment of the main vanes extending inwardly from theperiphery together with the tail-blades located back of them, and one ormore intermediate vanes extending from the periphery, or from some pointbetween the periphcry and the inlet circle, to or into the inlet circle,which intermediate vanes may or may not be provided with tail bladeslocated back of them as described.

What I claim as my invention and desire to secure by Letters Patent is-1; A centrifugal wheel for circulatingfluids, having a series of vanesextending inwardly from the periphery and blades back of the vanes, eachsuch blade extending inwardly toward its vane and at '11 greater anglefrom the radius than such vane, said wheel having an opening at or nearthe inner end of'the'blade leading into the space between the blade andvane.

2. A centrifugal wheel for circulating fluids, having a series of vanesextending inwardly from the periphery, and blades back of the vanes,each such blade extending inwardly toward its vane and at a greaterangle from the radius than such vane to a point between the inlet andthe periphery, said wheel having an opening atpr near the inner endofthe blade leading into the space between the vane and blade.

3. A centrifugal wheel for circulating fluids, having a series of vanesextending inwardly from the periphery, and blades back of the vanes,each such blnde extending inwardly toward its vane and at a greaterangle iron] the radius than such vane, said wheel having an opening atthe inner end of,said blade communicating with the space between thevane and blade.

4. A centrifugal wheel for circulating fluids, having a series of vanesextending inwardly from the periphery, and blades back of the vanes eachblade extending from the periphery inwardly toward its vane and at agreater angle from the radiusthan such vane to a point between ,theinlet and the periphery, said wheel having an opening at the inner endof said blade communicating with the space formed between the vane andthe blade.

5. A centrifugal wheel for circulating fluids,. having a.

tail-blade fitted at the back of a vane, which blade diverges from thevane as reckoned from the inner to the outer edge, a space intervalbeing provided between the inner edge of the biude'and the adjacentportion oi. the surface of the vane.

6; A centrifugal wheel for circulating fluids, comprising a series ofvanes so radially stepped relatively to one another that the second andeach of the-following vanes of the series is situated at a greaterradial distance from the center of rotation than the vane which nextprecedes it.

7'. A centrifugal wheel for circulating fluids, comprising a series ofvanes so radially stepped relatively to one an other that the second andeach of the following vanes oi the series is situated at a greaterradial distance from the center of rotation than the vane which nextprecedes it, and a tail blade fitted at the back of the most outwardlyextending portion of the terminal vane of the series.

8. A centrifugal wheel for circulating fluids, comprising a series ofvanes so radially stepped relatively to one another that the second andeach of the following vanes of the series is situated at a greaterradial distance from the center of rotation than the vane which nextprecedes it, and a tail blade iltted at the back of the most outwardlyextending portion of the terminal vane of the series which tail-bladeis, at its outer edge, inclined backward relativeiy' to the wheelperiphery more thzin the immediately preceding vane and, at its inneredge is separated from the back of the preceding vane.

9. A centrifugal wheel for circulating fluids, comprising a plurality ofseries of vanes so radially stepped relatively to one another that thesecond and each of the following vanes of the series is situated at agreater radial distance from the center of rotation than the vane whichnext precedes it and, interposed between each series, a vane whose outerportion is substituted for the terminal vane of the preceding series andinner portion for the leading vane of the succeeding series.

10. A centrifugal wheel for circulating fluids, comprising a pluralityof series of vanes so radially stepped relatively to one another'that'the second and each of the following vanes of the series is situated ata greater radial distance from the center of rotation than the vanewhich next precedes it and, interposed between each series, a vane whoseouter portion is substituted for the terminal vane of the precedingseries and inner portion for the leading-vane of the succeeding series,and a tail-blade fitted at the hackof the outward portion of each of themost radially extended vanes.

11. A centrifugal wheel for circulating fluids, comprising a series ofvanes so radially stepped relatively to one another that the second andeach of the following vanes of the series is situated at a greaterradial distance from the center of rotation than the vane whichnext'precedes it, the portion of a vane which lies within the air inletcircle having a scoop-shaped addition which extends laterally from thewheel.

12. Acentrifugal wheel for circulating fluids, comprising a plurality ofseries of vanes so radially stepped relatively to one another that thesecond and each of the fol- ,lowing vanes of the series is situated at agreater radial distance from the center of rotation than the vane whichseries of vanes extending inwardly from the periphery,

and blades back of said vanes, each such blade extending inwardly towardits vane and at a greater angle from the radius than such vane andterminating short of the inner end of the vane and leaving an openingbetween the inner end of the'blade and the vane.

14. A centrifugal wheel for circulating fluids, having a series of vanesextending inwardly from the periphery and concave in the direction ofrotation, and blades back of the vanes, each such blade extendinginwardly toward its vane and at a greater angle from the radius thansuch vane and terminating short of the inner end of the vane and leavingan opening between the inner end of the blade and the vane.

15. A centrifugal wheel for circulating fluids, having a series of mainvanes extending inwardly from the periphery, and one or more vaneslocated between said main vanes and extending from the inlet openingtoward the periphery but terminating short thereof. 7 I

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

GEonGE MARIE cAPEnL. Witnesses: v

FREDERICK WM. LANE, H. D. .TAMESON.

